Alright, let's work through 3901 times 4121 step by step
3901 × 4121 = 4121 × (3901)
+ 4121 × 1 which equals 4121
+ 4121 × 00 what gives us 0
+ 4121 × 900 producing 3708900
+ 4121 × 3000 yielding 12363000

= 16076021
